This invention relates generally to electromagnetic locks which are positioned for securing a doorway or entranceway. More particularly, the present invention relates to electromagnetic locks which are mounted at the top of the doorway and are energizable for electromagnetic bonding with an armature mounted to the door.
Electromagnetic locks have proved to be highly reliable for securing doorways, entranceways and the like. The recent trends in applications for electromagnetic locks have tended to require the use of increased electronics as a part of a more sophisticated overall security system. As the capabilities of electromagnetic locks have increased, it has become advantageous to provide additional on board electronic capability for each electromagnetic lock unit.
Conventional electromagnetic locks to which the invention relates, employ a metal core comprising a stack of generally E-shaped laminations. A coil is wound around the middle leg of the lamination stack. The lamination stack and the coil are mounted in a housing and the coil is potted to the core. The potting of the coil requires a separate manufacturing operation and ordinarily precludes an efficient and cost effective procedure for repairing the electromagnet by individually replacing a defective or malfunctioning coil or core assembly.
A common provision for mounting electronics within the electromagnet housing is to provide a compartment adjacent to the end of the electromagnet housing wherein access is provided from the face of the electromagnet unit. However, the available space provided by an end compartment is conventionally quite limited even though access to the compartment is readily obtained for both inswinging and outswinging door installations. A number of possible solutions for increasing the lock unit space capacity are subject to significant installation and operational constraints. For example, increasing the capacity of the compartment by enlarging the housing so as to extend downwardly a greater distance decreases the door clearance. Likewise, modifying the overall housing to lengthen the housing to expand the capacity of the compartment disproportionately lengthens the housing, detracts from the housing aesthetics, and undesirably increases the asymmetry associated with the conventional electromagnetic lock design. A long housing may also interfere with the door closer which is usually located in the vicinity of the housing.
Naturally, ready access to the electronics after installation is a desirable feature. Some conventional lock devices have incorporated electronic compartments which are located at the back of the electromagnetic lock unit. Such designs have greatly increased the capacity for mounting on board electronics. However, such designs are applicable only for outswinging doors. For inswinging door applications, the rear electronic compartment essentially does not afford any access without dismounting the lock unit.
Electromagnetic locks, including electromagnetic shear locks and electromechanical locks, bolts and electric strikes conventionally operate on either 12 volts DC or 24 volts DC power. It is common for a given electromagnetic lock to be capable of operating at either 12 VDC or 24 VDC and to be adapted so that at the time of installation, the lock may be adjusted for the proper operating voltage. Such operating voltage setting is frequently conventionally implemented by (a) a coil designed for one pre-established voltage; (b) two separate coils with four wires which are connected at the time of installation to accommodate the supply voltage; or (c) a manual selection switch which is set at the time of installation.